/* -*-c++-*- OpenSceneGraph - Copyright (C) Sketchfab
 *
 * This application is open source and may be redistributed and/or modified
 * freely and without restriction, both in commercial and non commercial
 * applications, as long as this copyright notice is maintained.
 *
 * This application is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#ifndef LINE_INDEX_FUNCTOR_H
#define LINE_INDEX_FUNCTOR_H

#include <osg/PrimitiveSet>
#include <osg/Array>

#include "Line"


template<class T>
class LineIndexFunctor : public osg::PrimitiveIndexFunctor, public T
{
public:
    virtual void setVertexArray(unsigned int,const osg::Vec2*)
    {}

    virtual void setVertexArray(unsigned int ,const osg::Vec3* )
    {}

    virtual void setVertexArray(unsigned int,const osg::Vec4* )
    {}

    virtual void setVertexArray(unsigned int,const osg::Vec2d*)
    {}

    virtual void setVertexArray(unsigned int ,const osg::Vec3d* )
    {}

    virtual void setVertexArray(unsigned int,const osg::Vec4d* )
    {}

    virtual void begin(GLenum mode) {
        _modeCache = mode;
        _indexCache.clear();
    }

    virtual void vertex(unsigned int vert) {
        _indexCache.push_back(vert);
    }

    virtual void end() {
        if (!_indexCache.empty()) {
            drawElements(_modeCache, _indexCache.size(), &_indexCache.front());
        }
    }

    virtual void drawArrays(GLenum mode, GLint first, GLsizei count) {
        switch(mode)
        {
            case(GL_LINES):
            {
                unsigned int pos = first;
                for(GLsizei i = 0 ; i < count ; i += 2, pos += 2) {
                    line(pos, pos + 1);
                }
            }
            break;
            case(GL_LINE_STRIP):
            {
                unsigned int pos = first;
                for(GLsizei i = 0 ; i < count - 1 ; i += 1, pos += 1) {
                    line(pos, pos + 1);
                }
            }
            break;
            case(GL_LINE_LOOP):
            {
                unsigned int pos = first;
                for(GLsizei i = 0 ; i < count - 1 ; i += 1, pos += 1) {
                    line(pos, pos + 1);
                }
                line(pos, first);
            }
            break;
            default: // not a line
            break;
        }
    }

    template<typename I>
    void drawElements(GLenum mode, GLsizei count, const I* indices)
    {
        if (indices == 0 || count == 0) return;

        switch(mode)
        {
            case(GL_LINES):
            {
                const I* iptr = indices;
                for(GLsizei i = 0 ; i < count ; i += 2, iptr += 2) {
                    line(*iptr, *(iptr+1));
                }
            }
            break;
            case(GL_LINE_STRIP):
            {
                const I* iptr = indices;
                for(GLsizei i = 0 ; i < count - 1 ; i += 1, iptr += 1) {
                    line(*iptr, *(iptr+1));
                }
            }
            break;
            case(GL_LINE_LOOP):
            {
                const I* iptr = indices;
                I first = *iptr;
                for(GLsizei i = 0 ; i < count - 1 ; i += 1, iptr += 1) {
                    line(*iptr, *(iptr+1));
                }
                line(*iptr, first);
            }
            break;
            default: // not a line
            break;
        }
    }

    virtual void drawElements(GLenum mode, GLsizei count, const GLubyte* indices) {
        drawElements<GLubyte>(mode, count, indices);
    }

    virtual void drawElements(GLenum mode,GLsizei count,const GLushort* indices) {
        drawElements<GLushort>(mode, count, indices);
    }

    virtual void drawElements(GLenum mode,GLsizei count,const GLuint* indices) {
        drawElements<GLuint>(mode, count, indices);
    }

    void line(unsigned int a, unsigned int b) {
        Line e(T::index(a), T::index(b)); // use remapped indices to deduplicate lines

        if(_lineCache.find(e) == _lineCache.end()) {
            this->operator()(a, b);
            _lineCache.insert(e);
        }
    }

    GLenum               _modeCache;
    std::vector<GLuint>  _indexCache;
    LineSet              _lineCache;
};

#endif
